The present invention relates to a carriage which travels on the outer surface of a pipe for inspecting, cleaning and/or painting the pipe.
A carriage which travels on the surface of a pipe is often used for inspecting a pipe to determine the degree of deterioration of the pipe. Most of the prior art carriages used for inspecting a pipe are manufactured substantially in accordance with the diameter of the respective pipe to be inspected. Among the known carriages, there are a number of carriages which move in the axial direction of the pipe and inspect the pipe, and are arranged as if they held the pipe in their arms. These known carriages have a structure such that an inspection in the circumferential direction of the pipe is carried out not by a movement of the carriage in the circumferential direction of the pipe, but by a movement of sensors and the like mounted on the carriage, which sensors are caused to revolve around the pipe.
The prior art carriage travelling on the surface of the pipe has had the following difficulties:
(1) In the prior art carriage arranged as if holding a pipe in its arms, at least two operators are required for attaching or removing the carriage to or from the pipe. This is inefficient and takes much time.
(2) Since the carriage is designed in accordance with the respective diameters of the pipes, a given carriage cannot be used for pipes of any other diameters, or it can be used only for pipes within a limited range of diameters.
(3) In the case of aerial pipes, wherein several pipes are arranged in parallel to one another or in parallel with other structural members, a range of the pipes which are objects of inspection is small, since some of the pipes are located so that it is difficult to install conventional carriages. In this case, the use of the prior art carriage which is arranged as if holding the pipes in its arms is limited.
(4) Since a mechanism of the carriage for clearing differences in level on the outer surface of a pipe is not sufficiently adjustable, manpower is required for attaching and removing the carriage to or from the pipe when such differences in level or when large surface irregularities are encountered.